The present invention relates to a method of assembling an optical fiber connector, and to an adhesive agent injecting jig for fixing an optical fiber to a ferrule to form an optical fiber connector.
Generally, as an optical fiber for transmission of optical signals, one or more optical fibers connected by connecting means such as connectors, welding and splices have been used. There are many cases in which optical fiber connectors and optical fiber cables having a high strength body for protecting a coated optical fiber from adverse influences to transmission of optical signals, such as a disturbance, and a coating sheath, such as PVC, are used. The optical fiber is usually made of brittle components such as glass, etc., and has a diameter which is as thin as 0.1 mm. Usually, nylon is sheathed around the optical fiber, which forms a coated optical fiber having a diameter of about 1 mm.
At the time of assembling the optical fiber cables and the optical fiber connectors, if the optical fiber connectors and the coated fiber of the optical fiber cable receive a local bending load due to compression forces, the optical signal transmitted therethrough is subjected to transmission loss, such as leakage of the optical signal to the outside, and to the disconnection of the optical transmission due to breakage of the coated optical fiber, etc.
Conventionally, when the optical fiber is fixed to a cylindrical ferrule having a penetrating hole at a center thereof, which constitutes an optical fiber connector, it is common to use an adhesive agent. FIGS. 2A and 2B are sectional views showing a conventional optical fiber connector assembling method in which an injection needle 40 is inserted directly into a cylindrical rear portion 42a of a ferrule 42. As shown in FIG. 2A, the injection needle 40 is inserted into a penetrating hole formed in the rear portion 42a of the ferrule 42, and an adhesive agent 43 is injected thereinto. Next, the injection needle 40 is removed and a coated or clad portion 44a of an optical fiber 44 having an exposed tip portion 44b whose coating or cladding has been removed is inserted through the rear portion 42a of the ferrule 42, so that the coated portion 44a and the exposed tip portion 44b of the optical fiber 44 are fixed to the ferrule 42 (FIG. 2B).
However, the foregoing conventional optical fiber connector assembling method suffers from the problem that the amount of the adhesive agent 43 must be controlled in order to prevent the overflow of the adhesive agent from the rear portion 42a of the ferrule 42 which is located at an innermost portion of a housing 45 of the optical fiber connector. Furthermore, since the rear portion 42a of the ferrule 42 is located at the innermost portion of the housing 45 of the optical fiber connector, it has been difficult to remove the overflowed adhesive agent 43. Yet another problem with the conventional optical fiber connector assembling method is that the ferrule 42 cannot be moved in the axial direction, since the adhesive agent 43 overflows to a location intermediate between the rear portion 42a of the ferrule 42 and the housing 45, and to a location on which a coil spring 46 is mounted, thereby firmly fixing the ferrule 42 to the inside of the housing 45.